The present disclosure relates generally to aerospace components used in gas turbine engines and more particularly to methods and apparatuses for application of a low heat weld.
Gas turbine engines, such as those that power modern commercial and military aircraft, generally include a compressor section to pressurize an airflow, a combustor section to burn a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases.
Arranged within the compressor and turbine sections are alternating annular stages of circumferentially disposed rotational blades and stationary vanes. The blades are typically mounted on a disk that rotates about its central axis though integrally bladed rotors (IBR) and blades referred to as BLISKS in the industry may also be used. The blades and vanes are typically forged from superalloys such as a nickel-base alloy. In addition, the casting is frequently performed so as to produce a directionally solidified part with grains aligned parallel to the axis of the blade or a single crystal part, with no grain boundaries.
Some gas turbine engine blades are designed so that during engine operation, the tip portion of the rotating blades rubs a stationary seal or case to limit the leakage of working medium gases. While the seals are usually more abradable than are the blade tips—so that during such rub interactions, a groove is cut into the seal—the blade tips do wear, and the blades become shorter. As the blades accumulate service time, the total tip wear increases to the point that eventually, the efficiency of the blade and seal system may be reduced such that the blades need to be repaired or replaced. Repairs are typically more efficient.
Several methods exist for repair. The tips of worn blades can be repaired, and the length of the blade increased, by removal, or the worn and/or damaged tip area then weld filler metal is used to the tip to build up the tip to a desired dimension. Such weld filler repairs may import a significant quantity of heat into the component such that relatively thin components may only accept a limited build up of weld material which limits the length increase.